I unfortunately cannot give this app a very favourable review because it is missing many common words. I have a paper dictionary that I use more often. It's free, so it has that going for it but most of the time you can't find the word you are looking for in it. Seriously, even common words like "Sibling" cannot be found. And it's not just the English word section that is limited. Even if you put Korean words in, many times it will show nothing.
This app needs more work before it can be fairly judged.